SERPINC1 and hereditary antithrombin deficiency: The last potential regulatory genetic variation identified in patients with antithrombin deficiency but with not mutations or gross deletions in exons or flanking regions of SERPINC1 was discovered in P4 (Table 1), an African woman with moderate antithrombin deficiency (78% of anti-FXa activity) who suffered a deep venous thrombosis and a pulmonary embolism at the age of 42,one month after receiving major chemotherapy due to an invasive ductal carcinoma.